Multiple expansion engine



Oct. 30, 1934. w. KLEIN ET AL MULTII LE EXPANSION ENGINE 3 Sheets-Sheet 1 Filed Oct. 6, 1932 061. so, 1934. 1 w, KLEI ETAL 1,979,161

MULTIPLE EXPANSION ENGINE Filed Oct. 6. 1932 3 Sheets-Sheet 2 1934- w. KLEIN ET AL 1,979,161

MULTIPLE EXPANSION ENGINE Filed Oct. 6, 1932 3 Sheets-Sheet 3 Patented Oct. 30, 1934 urrs srATss await].

NIULTIPLE EXPANSF ION ENGINE Wilhelm Klein, Oscherslcben, and Georg Moering, Kotzschenbroda, Germany Application October 6, 1932, Serial No. 636,588 In Germany October 12, 1931 8 Claims.

The present invention relates to control mechanism fordouble cylinder steam engines having slide valveswithout connecting rods, as required particularly for the actuation of boiler feed pumps. It has already been proposed to cause the individual control elements to be moved by steam, by drag valves moved by the piston rod or the pistons, or by the working pistons themselves, but none of these methods have been sufficiently reliable in function. This is due, particularly in the case of locomotive boiler feed pumps, to the fact that the reversal of stroke without a changed piston play causes impacts or shocks in the feed conduit which fracture the pipes and feed valves and render the preheater pipes leaky. For maintaining the piston play, it is therefore necessary to increase the working safety of the pumps.

For this purpose, according to the present invention, the first working piston moves mechani- 'cally both the control slide valve of the second working piston and the preliminary control valve, constructed as a drag valve, of its own steam-actuated main control valve. Thus the main control of the one working piston, and the preliminary control of the other, are effected purely mechanically by the first working piston.

The actuation can be derived in known manner from the piston rod, for instance by means of an externally located single-armed lever .Iwhich simultaneously reducesthe stroke of the slide valve in relation to the piston stroke, or by means of a rigid arm. It can howeveralso be located inside the steam spaces of the working cylinders and be actuated from the piston itself.

This method of control is suitable both for twin and for, compound arrangement of the steam cylinders.

Reference will now be made to the accomfpanying drawings, in which three different constructions of compound engines with receiver are illustrated.

Figure 1 is a sectional view taken on the axes of the cylinders and valves showing a first embodiment of the invention.

Figure 2 is a corresponding View of the second embodiment, substantially on line 2-2 of Fig. 3.

Figure 3 is a transverse sectional view substantially on line 33 of Figure 2, with the pistons and valves eliminated for clearness.

Figure 4 is an axial sectional view substantially on line l4 of Fig. 6, showing a third embodiment of the invention.

igure 5 is a sectional view substantially on line 5-5 of Fig. 6.

Fi ure 6 is a transverse sectional view substantially on line 6-6 of Figure 4, with the pistons removed for clearness.

Figure 7 is an axial sectional view of a fourth embodiment of the invention, substantially on line 7-7 of Fig. 8.

Figure 8 is a transverse sectional view substantially on line 8-8 of Fig. 7.

Figure 9 is a fragmentary sectional view with the control piston and associated parts removed, substantially on line 9-9 of Fig. 8.

In Figure 1, the high pressure piston Hp in the high pressure cylinder He has two heads and moves the distribution slide valve 7 of the low pressure cylinder L in the second half of the stroke by direct impact of the inner edges of its heads. The control for the high pressure cylinder is constituted by the known con trol with steam actuated main slide valve 14 and preliminary control drag valve 9, in which the preliminary control valve is actuated by the high pressure piston rod Hr by means of a single armed lever G and rod 8. In the various figures, the inlet for fresh steam is at connectic-n E, and the final exhaust occurs from chamber A. The receiver R or Be is located between the stages.

In Figures 2 and 3, a horizontal compound engine is illustrated, wherein the low pressure cylinder L0 is disposed above the high pressure cylinder He which is surrounded by the receiver R for the purpose of facilitating the flow of the condensed water from the low pressure cylinder and for the purpose of heating the receiver by the high pressure cylinder Ho. The distributing slide valve 7 of the low pressure cylinder Lo and the preliminary control valve 9 of the high pressure cylinder 1-10 are disposed parallel to the cylinder axes and are moved by a common slide rod 8a, which is operated by means of a lever G by the working piston rod Hr of the high pressure cylinder in similar manner to the previous construction.

In Figs. 4, and 6 the working cylinders Ho and Lo are located adjacent each other and the control valve 7 of the low pressure cylinder L0 and the preliminary control valve 9 in its housing 9a of the high pressure cylinder Hc are disposed perpendicularly to the cylinder axes and moved by a common slide rod 82) which however is in this case controlled by a thrust block having an oblique groove which is actuated by the piston rod Hr of the high pressure cylinder Ho through the intermediary of a rigid arm B and rod 30a.

In Figs. 7 and 8, the actuation of the control mechanism is efiected internally from the high pressure piston Hp, the common slide rod for the preliminary control valve 9 of the high pressure cylinder and the control valve '7 of the lower pressure cylinder being actuated by means of a slide block 6 which is moved by the walls of an oblique groove 3 in the middle portion I-In between the two heads of the high pressure piston which is formed as a long piston.

Fig. 9 illustrates a section taken through the slide valve chest.

This form of construction is particularly useful for direct-action upright boiler feed pumps for locomotives.

The space between the two heads of the high pressure, piston is in communication with the receiver'Ra by port 2 and is sealed from the working spaces at the ends of the high pressure cylinder He by means of piston rings in the two piston heads. A second groove 4 disposed in the middle portion Hm parallel to the movement of the piston Hp prevents rotation of the long piston Hp by engaging the element 5 secured in the wall of the working cylinder Ho.

The actuating arm 6 of the slide rod 80 passes through the aperture 2 of the cylinder wall and engages in the oblique groove 3. The two slide valves 7 and 9 may be constructed as flat slide valves and also as piston slide valves. Instead of the actuating arm 6, a slide block may engage in the groove 3, this block being adapted to operate the slide rod 80 by means of an internally disposed transmission lever.

In the arrangement illustrated, the arm 6 actuates, on the low pressure side, the distribut- :ing slide valve '7 of the low pressure cylinder Lc which is constructed as a flat slide valve, and

on the high pressure side actuates the preliminary control piston valve 9 for the distributing piston valve 1-122 of the high pressure cylinder He.

The mechanism described is located in a slide valve chest 11 which is permanently connected to the receiver Ra.

The distributing valve '7 of the low pressure cylinder Lc stands approximately in its middle position when the high pressure piston Hp actuating it. passes through the centre of its stroke. As the closure or lap portions of the flat side valve 7 are very narrow, the walls of the oblique groove 3 advancing with the high pressure piston Hp must push on the actuating arm 6 and the slide rod 80 and the distributing valve 7 are moved at right angles to the movement of the working piston Hp until shortly after passin the centre of the stroke of the high pressure piston, when it opens the corresponding steam inlet channel 28 or 29 of the low pressure cylinder in the slide valve chest 11, that is to say, connects this cylinder with the receiver Ra.

The low pressure piston Lp thus changes its stroke shortly after the high pressure piston Hp has passed the centre of its stroke.

The preliminary control valve 9 is a drag valve which is only carried along by the thrust rod 80 as the latter approaches the ends of its strokes. The stops on the thrust rod 80 provided for this purpose are constituted by adjustable double nuts Bar.

The preliminary control valve 9 is constituted by a piston slide valve which is formed with two piston heads or collars at its ends and with an open central passage, and works in the receiver steam without tendency toward endwise movement by differential pressures. Fresh inlet steam is always present in the entry space 12 between the two piston heads, by movement through passage 26 from the inlet connection E, and is delivered by the preliminary control valve 9, as required, through the passage 25 to the control cylinder 10 of the high pressure cylinder main control Hm for the purpose of displacing the same. This steam may be withdrawn from the cylinder 10 by passage 24 upon movement of the valve 9, and led oil to the receiver Ra. The main control for the high pressure cylinder is formed by a differential piston with a large control piston head 14 and the three smaller piston heads 15, 16 and 1'7, and with reduced connecting portions providing spaces l3, l9 and 18. This piston works in the control cylinder 10. The control piston head 14 is operated in known manner, as the preliminary control valve 9 alternately admits fresh steam to the upper full control cylinder space 20 by passage 25, or permits the escape of steam therefrom through passage 26, so that the inlet steam operating differentially in the space 13 on the annular piston surfaces of piston heads 14 and 15 is either overcome or assumes control.

The spaces 13 and 18 form the entrance chainbers and the middle space 19 constitutes the exit chamber for the control of steam moving to and from the high pressure cylinder He by passages 13a and 19a. Thus, with the differential control piston H12 in the position of Figure 7, steam entering through the inlet E (Figure 8) passes to the spaces 27 from whence it moves to the space 13, annular space 13a and the corresponding passage to the upper end of the high pressure cylinder Hc. At the same time, exhaust occurs from the. lower end of this cylinder" Hc by passages 19a to space 19, passage 1% and passage 23 to the receiver. Upon the movement of the diiferential control piston 9 to its uppermost position, steam from the inlet chamber 27 flows to space 18 and thence to passages 19a to the lower end of the high pressure cylinder He; while exhaust is occurring by passages 13a and space 19, passages 19b and 23 to the receiver.

The downward movement (Figure 7) of: the differential piston is damped by the lower piston head 17, and the upward movement by the control piston head 14, as the corresponding piston head travels past the corresponding outlet opening 24 or 22, and sets up compression in the end spaces 20 or 21, which, arethus sealed off. The end spaces 20 and 21 do not blow on into the open air, but into the receiver Ra and, after the heads 14 and 17 seal off the passages from these spaces, the exhaust receiver steam is compressed in these spaces.

For this purpose, the control cylinder 10 has the separate paths for delivering and discharging the control steam. The control steam is delivered from the preliminary control valve 9 through the inlet channel 25 as aforesaid, and is led off through the outlet channel 24. The outlet channel 24 opens into the control cylinder 10 at a distance from the-.upper limit of travel of the control piston head 14, and is covered by the control piston head 14 before this head reaches the upper end of its stroke (Figures 7 and 9). The inlet channel 25 remains open with respect to the space 20, but during the outlet its periods of the latter is closed by the control valve 9.

In this manner, a more efiicient damping of the inertia effect of the steam-controlled differential piston H0 is obtained than when the discharge occurs to the open air.

In the extreme left hand position of the preliminary control valve 9, the control steam is out 01f from the space 12 and the control cylinder space 20 is discharged through the channel 24 to the receiver Ra.

Commencing from the position shown in Figs. 7 and 8, the phases of control in the engine operating with this group of steam cylinders is as follows when the engine is set in operation;

The steam enters at E into the space 27 and thence passes into the entrance chambers 13 and 18, through the channel 26 into the space 12 of the preliminary control slide valve 9, and through the channel 25 to the upper control cylinder space 20. Displacement of the diiferential piston Hv cannot take place because the pressure on the upper full control piston surface of the head 14 in space 20 is greater than on the annular lower surface of head 14 (position of Figure 7).

From the entrance space 13, the fresh steam has passed through the upper steam port 13a into the upper working space of the high pressure cylinder Hc while, on the other hand, the lower working space empties itself through the lower steam port 190 and the outlet channels 19b and 23 into the receiver.

The high pressure piston Hp moves downwards. As it passes the centre of its stroke, its oblique groove 3 has pushed the actuating arm 6 with the distributing slide valve '7 further to the left (Fig. 8) and opens the upper steam channel 28 to the low pressure cylinder for the flow of the receiver steam into its upper Working space.

At the same time the outlet of the lower low pressure cylinder working space is connected by the lower steam channel 29 to the exhaust space preliminary A. The low pressure cylinder N begins to move downwards.

The advancing high pressure piston Hp near the end of its downward stroke causes the arm Gand the rod So to actuate the preliminary control piston 9 and thereby changes, in its preliminary control cylinder, the control channels for the control piston head 14 of the diiferential piston Ho.

The fresh steam in the space 12 of the preliminary control slide valve 9 is shut off at the channel 25. The right hand outer edge of this slide valve 9 opens the channel 24 and thus empties the cylinder space 20 to the receiver Ra. In this manner, the fresh steam pushing against the lower annular surface of the control piston head 14 assumes control and pushes the differential ,piston Ho upwardly.

Consequently entrance and exit through ports 13a and 19a are changed at the high pressure cylinder and the high pressure piston Hp begins to move upwards.

.The preliminary control piston 9 is not at once influenced by the counter movement of the thrust rod 8 commencing at the same time. At first, it remains at a standstill, as it is constructed as a drag valve, and is only carried along, that is displaced, when the high pressure piston Hp approaches the upper end of its stroke.

The reversal of stroke of the low pressure piston is commenced at the lower end of the stroke whenthe upwardly travelling high pressure piston has passed through the centre of its stroke.

As the high pressure piston Hp positively controls the distributing valve '7 of the low pressure cylinder directly, the strokes of the two working pistons are reversed at different times, and their successive action is thus definitely ensured.

The operation of the embodiments illustrated in Figs. 1 to 6 corresponds exactly to that above described and the reference numerals shown therein correspond to those used in Figs. 7 to 9.

We claim:

1. A double cylinder steam engine comprising a first steam cylinder and piston and a valve for controlling the admission and exhaust of said first cylinder, a second steam cylinder and piston and a valve for controlling the admission and exhaust of said second cylinder, means actuated by said first piston in its movement for operating said second valve whereby said second'valve is reversed during the course of the stroke of said first piston, and further means actuated by said first piston at the ends of its stroke for operating said first valve whereby said first valve is reversed at the ends of the stroke of said first piston, said further means including a lost motion device whereby the actuation of said first valve occurs only at the ends of the stroke of said first piston.

2. A double cylinder steam engine comprising a first steam cylinder and piston and a valve for controlling the admission and exhaust of said first cylinder, 2. second steam cylinder and piston and a valve for controlling the admission and exhaust of said second cylinder, means actuated by said first piston in its movement for operating said second valve whereby said second valve is reversed during the course of the stroke of said first piston, and means moved by said actuating means at the ends of its stroke for operating said first valve whereby said first valve is reversed at the ends of the stroke of said first piston.

3. An engine as in claim 1, in which said further means includes a lever actuated by said first piston, a rod moved by said lever, said second valve being directly connected to said rod, and said first means includes control means for said first valve arranged coaxially with said second valve, said rod and said control means including cooperating elements providing a lost motion device whereby said rod only ctuates said control means at the ends of the stroke of said first piston.

4. An engine as in claim 1, in which said means includes a common slide rod disposed perpendicularly to the axes of the cylinders, said first piston having an oblique groove thereon, means for preventing rotation of said first piston about its aXis, and means connected to said slide rod and engaged in said groove for reciprocation by the Walls thereof during the movement of said first piston, said valves being operated by said common slide rod.

5. An engine as in claim 1, in which said first piston has two heads and a reduced portion therebetween, said reduced portion being provided with an oblique groove, a control member located perpendicularly to the axis of said first piston, a device connected to said control member and extending into said groove so that the control member is reciprocated during the movement of. said first piston, and connections be-- tween said control member and said valve.

6. An engine as in claim 1, in which said first valve includes a main control piston head and said first means includes a'preliminary control device which controls the selective admission to and, exhaust of steam from the end surfaces of said control piston.

7. A double cylinder steam engine comprising a high pressure steam cylinder and piston and a'valve for controlling the admission and exhaust of said high pressure cylinder, a low pressure: steam cylinder and piston and a valve for controlling the admission and exhaust of said low pressure cylinder, 2, receiver surrounding said high pressure cylinder, means actuated by said high pressure piston in its movement for operating said low pressure valve for controlling theadmission of steam from said receiver to said low pressure cylinder and for reversing said low pressure valve during the course of the stroke of said high pressure piston, and further means actuated by said high pressure piston at the ends of its stroke for operating said high. pressure valve for the escape of steam from said high pressure cylinder to said receiver and the admission of steam to said high pressure cylinder whereby said high pressure valve is reversed: at-the ends of the stroke of said high.

pressure piston.

8. A double cylinder steam engine comprising a first steam cylinder and piston and a valve for controlling the admission and exhaust of said first cylinder, a second steam cylinder and piston and a valve for controlling the admission and exhaust of said second cylinder, said first pistonhaving two heads with a reduced portion therebetween, means including a device extending into the space between said heads and alternately actuated by said heads during the movement of said first piston for operating said second valve whereby said second valve is reversed during the course of the stroke of said first piston, and further means actuated by said first piston at the ends of its stroke for operating said first valve whereby said first valve is reversed at the ends of the stroke of said first piston, said. further means including a rod having. spaced abutments thereon, and means on said first valve selectively actuated by said abutments and being free of said abutments during the major portionlof the stroke of said first piston.

WILHELM KLEIN.

GEORG MOERING. 

